/* This file contains parts of the KDE libraries
   Copyright (C) 1999 Ian Zepp (icszepp@islc.net)
   Copyright (C) 2006 by Dominic Battre <dominic@battre.de>
   Copyright (C) 2006 by Martin Pool <mbp@canonical.com>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/

#include "qnaturalsorting.h"

//from KDE
/*
int naturalCompare(const QString &_a, const QString &_b, Qt::CaseSensitivity caseSensitivity)
{
    // This method chops the input a and b into pieces of
    // digits and non-digits (a1.05 becomes a | 1 | . | 05)
    // and compares these pieces of a and b to each other
    // (first with first, second with second, ...).
    //
    // This is based on the natural sort order code code by Martin Pool
    // http://sourcefrog.net/projects/natsort/
    // Martin Pool agreed to license this under LGPL or GPL.

    // FIXME: Using toLower() to implement case insensitive comparison is
    // sub-optimal, but is needed because we compare strings with
    // localeAwareCompare(), which does not know about case sensitivity.
    // A task has been filled for this in Qt Task Tracker with ID 205990.
    // http://trolltech.com/developer/task-tracker/index_html?method=entry&id=205990
    QString a;
    QString b;
    if (caseSensitivity == Qt::CaseSensitive) {
        a = _a;
        b = _b;
    } else {
        a = _a.toLower();
        b = _b.toLower();
    }

    const QChar* currA = a.unicode(); // iterator over a
    const QChar* currB = b.unicode(); // iterator over b

    if (currA == currB) {
        return 0;
    }

    const QChar* begSeqA = currA; // beginning of a new character sequence of a
    const QChar* begSeqB = currB;

    while (!currA->isNull() && !currB->isNull()) {
        if (currA->unicode() == QChar::ObjectReplacementCharacter) {
            return 1;
        }

        if (currB->unicode() == QChar::ObjectReplacementCharacter) {
            return -1;
        }

        if (currA->unicode() == QChar::ReplacementCharacter) {
            return 1;
        }

        if (currB->unicode() == QChar::ReplacementCharacter) {
            return -1;
        }

        // find sequence of characters ending at the first non-character
        while (!currA->isNull() && !currA->isDigit() && !currA->isPunct() && !currA->isSpace()) {
            ++currA;
        }

        while (!currB->isNull() && !currB->isDigit() && !currB->isPunct() && !currB->isSpace()) {
            ++currB;
        }

        // compare these sequences
        const QStringRef& subA(a.midRef(begSeqA - a.unicode(), currA - begSeqA));
        const QStringRef& subB(b.midRef(begSeqB - b.unicode(), currB - begSeqB));
        const int cmp = QStringRef::localeAwareCompare(subA, subB);
        if (cmp != 0) {
            return cmp < 0 ? -1 : +1;
        }

        if (currA->isNull() || currB->isNull()) {
            break;
        }

        // find sequence of characters ending at the first non-character
        while (currA->isPunct() || currA->isSpace() || currB->isPunct() || currB->isSpace()) {
            if (*currA != *currB) {
                return (*currA < *currB) ? -1 : +1;
            }
            ++currA;
            ++currB;
        }

        // now some digits follow...
        if ((*currA == '0') || (*currB == '0')) {
            // one digit-sequence starts with 0 -> assume we are in a fraction part
            // do left aligned comparison (numbers are considered left aligned)
            while (1) {
                if (!currA->isDigit() && !currB->isDigit()) {
                    break;
                } else if (!currA->isDigit()) {
                    return +1;
                } else if (!currB->isDigit()) {
                    return -1;
                } else if (*currA < *currB) {
                    return -1;
                } else if (*currA > *currB) {
                    return + 1;
                }
                ++currA;
                ++currB;
            }
        } else {
            // No digit-sequence starts with 0 -> assume we are looking at some integer
            // do right aligned comparison.
            //
            // The longest run of digits wins. That aside, the greatest
            // value wins, but we can't know that it will until we've scanned
            // both numbers to know that they have the same magnitude.

            bool isFirstRun = true;
            int weight = 0;
            while (1) {
                if (!currA->isDigit() && !currB->isDigit()) {
                    if (weight != 0) {
                        return weight;
                    }
                    break;
                } else if (!currA->isDigit()) {
                    if (isFirstRun) {
                        return *currA < *currB ? -1 : +1;
                    } else {
                        return -1;
                    }
                } else if (!currB->isDigit()) {
                    if (isFirstRun) {
                        return *currA < *currB ? -1 : +1;
                    } else {
                        return +1;
                    }
                } else if ((*currA < *currB) && (weight == 0)) {
                    weight = -1;
                } else if ((*currA > *currB) && (weight == 0)) {
                    weight = + 1;
                }
                ++currA;
                ++currB;
                isFirstRun = false;
            }
        }

        begSeqA = currA;
        begSeqB = currB;
    }

    if (currA->isNull() && currB->isNull()) {
        return 0;
    }

    return currA->isNull() ? -1 : + 1;
}

*/
static inline QChar getNextChar(const QString &s, int location)
{
    return (location < s.length()) ? s.at(location) : QChar();
}

int naturalCompare(const QString &s1, const QString &s2,  Qt::CaseSensitivity cs)
{
    for (int l1 = 0, l2 = 0; l1 <= s1.count() && l2 <= s2.count(); ++l1, ++l2) {
        // skip spaces, tabs and 0's
        QChar c1 = getNextChar(s1, l1);
        while (c1.isSpace())
            c1 = getNextChar(s1, ++l1);
        QChar c2 = getNextChar(s2, l2);
        while (c2.isSpace())
            c2 = getNextChar(s2, ++l2);

        if (c1.isDigit() && c2.isDigit()) {
            while (c1.digitValue() == 0)
                c1 = getNextChar(s1, ++l1);
            while (c2.digitValue() == 0)
                c2 = getNextChar(s2, ++l2);

            int lookAheadLocation1 = l1;
            int lookAheadLocation2 = l2;
            int currentReturnValue = 0;
            // find the last digit, setting currentReturnValue as we go if it isn't equal
            for (
                QChar lookAhead1 = c1, lookAhead2 = c2;
                (lookAheadLocation1 <= s1.length() && lookAheadLocation2 <= s2.length());
                lookAhead1 = getNextChar(s1, ++lookAheadLocation1),
                lookAhead2 = getNextChar(s2, ++lookAheadLocation2)
                ) {
                bool is1ADigit = !lookAhead1.isNull() && lookAhead1.isDigit();
                bool is2ADigit = !lookAhead2.isNull() && lookAhead2.isDigit();
                if (!is1ADigit && !is2ADigit)
                    break;
                if (!is1ADigit)
                    return -1;
                if (!is2ADigit)
                    return 1;
                if (currentReturnValue == 0) {
                    if (lookAhead1 < lookAhead2) {
                        currentReturnValue = -1;
                    } else if (lookAhead1 > lookAhead2) {
                        currentReturnValue = 1;
                    }
                }
            }
            if (currentReturnValue != 0)
                return currentReturnValue;
        }

        if (cs == Qt::CaseInsensitive) {
            if (!c1.isLower()) c1 = c1.toLower();
            if (!c2.isLower()) c2 = c2.toLower();
        }
        int r = QString::localeAwareCompare(c1, c2);
        if (r < 0)
            return -1;
        if (r > 0)
            return 1;
    }
    // The two strings are the same (02 == 2) so fall back to the normal sort
    return QString::compare(s1, s2, cs);
}
bool naturalSortLessThanCS( const QString &left, const QString &right )
{
  return (naturalCompare( left, right, Qt::CaseSensitive ) < 0);
}

bool naturalSortLessThanCI( const QString &left, const QString &right )
{
	return (naturalCompare( left, right, Qt::CaseInsensitive ) < 0);
}

bool naturalSortLessThanCIFileInfo(const QFileInfo & left,const QFileInfo & right)
{
	return naturalSortLessThanCI(left.fileName(),right.fileName());
}
